At the Old Bailey yesterday, Reilly – who appeared as Mohammad Rashid Saeed Alim – pleaded guilty to attempted murder on May 22 and to preparing terrorist acts.

A prosecutor said: “He told police he intended to martyr himself and to kill others.

“In his words, this was in retaliation for the oppression of Muslims around the world and in relation to world events of recent years.”

Reilly used the internet to research how to make bombs in soft drinks bottles.

He discussed with two unidentified people in a website called Chechen222 whether to kill police officers or other public servants or ordinary citizens. He settled on ordinary citizens.

Police arrested Reilly, who has Asperger’s syndrome and a mental age of 10, at the scene.

They believe he was preyed upon and groomed by extremists online after he converted to Islam five years ago and attended prayers near his Plymouth home.

Detectives are still hunting unidentified others involved.

His mother, Kim Reilly, yesterday blamed fanatics in Pakistan for “brainwashing” him through his YouTube page. She claimed that due to his learning difficulties, her son should be sent to a mental hospital not prison when he returns to court for sentencing next month.

She said: “There’s no way Nicky’s got the capability to do that. He’s so vulnerable, he’s got special needs.

“Somebody has brainwashed him…and they’re walking free.

He does not need to be in prison, he needs to be in hospital.”

A counter-terrorism official said: ” There are people out there looking for vulnerable, impressionable young Muslims using chatrooms who can be manipulated into planning and carrying out attacks.”